In existing, centrally controlled communications installation, information regarding the type, equipment features and terminal positions of connected communications terminal equipment is predominantly stored in the communications installation. In predominantly program-controlled communications installation, this information is usually defined by suitable program parameters. The data for every communications terminal equipment are thereby separately stored in a region provided therefor in the database that is usually established in a program-controlled communications installation. With the use of this data that describes the type, equipment and position of the communication terminal equipment, and with suitably implemented programs, the exchange, maintenance and servicing functions allocated to the communication terminal equipment are realized in the communications installation. For some time, a frequent modification of the program parameter data has been required because of more complex communications terminal equipment and exchange, maintenance and servicing functions, particularly subscriber performance features. Due to the use of microprocessors and microcomputers, a part of the "intelligence" of the communications installation, i.e. a part of the functions, particularly input and output functions associated to the performance features and communications terminal equipment, that are realized in the communications installation can be moved into the communications terminal equipment. This means that at least one part of the program parameter data, those relevant for the respective communication terminals equipment, must be present in every communications terminal equipment in a memory provided for this purpose.
Further, German patent application No. P 37 32 679.1 proposes a method for code-transparent transmission of information in the signalling channel of a communications terminal equipment, whereby a message-oriented transmission protocol is employed. This message protocol is fundamentally defined by:
a start of message information;
an information that allows the summary check of the information of an information part (for example, by specifying the plurality of transmitted bits or bytes);
a message code information that indicates the type of message;
an information part that contains the information to be transmitted; and
an end of message information.
What is thereby involved is a message protocol that is utilized between communications installation and communications terminal equipment for information exchange, for example signalling and maintenance information. The communications terminal equipment can thereby be realized both by a subscriber terminal equipment, for example, telephone, teletex apparatus, as well as by a servicing or maintenance means.